ATYPICAL PRESENTATION OF GRANULOMATOSIS WITH ANCA-NEGATIVE POLYANGIITIS: CASE Report

Abstract

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis are systemic inflammatory diseases in which diagnosis often relies on a compatible clinical presentation and ANCA positivity. Some cases, especially forms limited to the kidneys, may be ANCA-negative, which can delay recognition and treatment. We report the case of a 73-year-old woman with multiple comorbidities and a solitary kidney (left nephrectomy in 2008) who presented with asthenia, nausea, and rapidly progressive worsening of renal function. Despite supportive management and exclusion of infectious, obstructive, and hemodynamic causes, kidney function continued to decline, leading to hemodialysis dependence. Autoimmune investigation showed normal complement levels and negative antinuclear antibodies, immunofixation, and ANCA. In the absence of a diagnosis and the progressive clinical course, renal biopsy was performed despite the technical concerns related to a solitary right kidney. Histopathology revealed pauci-immune crescentic glomerulonephritis with arterial vasculitis, supporting a diagnosis of ANCA-negative granulomatosis with polyangiitis. The patient received pulse methylprednisolone followed by cyclophosphamide, with gradual improvement and partial recovery of renal function, allowing dialysis discontinuation after 2–3 months. At 8 months of follow-up, renal function remains stable on low-dose immunosuppression. This case emphasizes that negative ANCA serology does not exclude severe AAV and illustrates how biopsy can be the turning point that enables timely, disease-specific treatment, even in fragile and high-risk clinical scenarios.